1. Field of the Invention
The present invention relates to a molded resin object that contains a biodegradable resin and has an applied coating on a surface thereof, an electronic instrument using it, and a method of processing a molded resin object.
2. Description of the Related Art
Under the increasing of resource conservation and environmental conservation, electronic products have been developed in which the disposal of the product, after the end of the service life thereof or when the product that is no longer required, such as by incineration, recycling (reutilization), reuse (reusing), and dumping, is taken into consideration.
Meanwhile, a conventional plastic made from petroleum as a raw material, such as poly(ethylene) and poly(styrene), has excellent properties of lightness in weight, high strength, and long service life. Since such a plastic emits high heat in an incineration process so as to damage the incinerator and generates a hazardous substance such as dioxin, disposal of it in a landfill has been mainly conducted to date. Moreover, since a plastic case has a high volume per weight, much space is required for incineration. Further, since conventional plastic is hardly decomposed in soil, the problems of environmental damage occur such as an exposed plastic product spoils the natural beauty and has an adverse effect on wildlife. Thus, processing of the conventional plastic after the use thereof has seldom been taken into consideration.
Recently, a biodegradable resin with a significantly higher rate of biodegradation in soil or water than conventional plastics has being developed. A biodegradable resin refers to a plastic decomposed by the biodegradation ability of a microbe in soil or water, which is, for example, converted to water and carbon dioxide when it is completely decomposed by a microbe. As a biodegradable resin, for example, there can be provided polylactide synthesized from starch, that is, polylactic acid, and poly(ε-caprolactone). In regard to a biodegradable resin, the resin materials and application products thereof, for example, a housing for an electronic instrument, commodities such as a plastic bag, a sheet, a flower pot and fibers, parts of an automobile, and a substituting case of a plastic case for foods are actively being developed. The biodegradable resin not only has good biodegradability in soil but also generates global warming gas such as carbon dioxide and heat in quantities less than a petroleum-derived resin at the time of incineration, and therefore is an earth-conscious material.
A case or sheet in which an applied coating is formed on a surface of a molded item of such a biodegradable resin which coating is also composed of a biodegradable resin is proposed in, for example, Japanese Laid-Open Patent Application Nos. 5-278738 and 2003-165570.
However, where the case or sheet disclosed in Japanese Laid-Open Patent Application No. 5-278738 or 2003-165570 is buried in the ground, the problem is that the rate of biodegradation of the case or sheet is slow such that it takes approximately 1 year through 2 years to decompose it due to microbes in the soil.